Apparatus and method for producing inert gas



April L. K. cscu. ETAL 2,418,162

APPARATUS AND METHOD FOR PRODUC ING INERT GAS Filed July 19, 1944 Patented Apr. 1, 1947 APPARATUS AND METHOD FOR PRODUCING INERT' GAS Lawrence K. Cecil, Rudolph J. Stengl, and Floyd B. Bedwell, Tulsa, Okla, assignors to Ozark Chemical Company, Tulsa, Okla., a corporation of Delaware Application July 19, 1944, Serial No. 545,670

. 6 Claims.

Inert gas is being employed in increasing quantities in various industrial applications but the Y apparatus heretofore utilized for generating the gas by combustion of suitable fuel in the air is frequently not particularly efficient from the standpoints of convenience, operating economy and the like.

It is therefore an object of our invention to provide an apparatus for producing inert gas, normally consisting principally of nitrogen, carbon dioxide and a small amount of water vapor and devoid or substantially devoid of nitric oxide, by the submerged combustion of a gaseous fuel.

A further object of the invention is the provision of apparatus of the character aforesaid so drain connection 4. An inlet pipe 5 extends upwardly from the burner, the lower end of which may be steadied within the tank by a spider" 6, to a suitable point above the cover, where it receives a connection I for directing into it the combustible mixture of air and a suitable gas, such as natural gas.

For supplying the air component of the mixture a fan or blower l0 conveniently motor driven is disposed at a suitable point and an air inlet pipe I l, which may be provided with a relief valve designed that it is substantially automatic in i l operation and thus require little or no attentian over longperiods of time, but which in case of accidental failure of the gas generating flame is effective to prevent contamination of the previously generated gas by unconsumed combustible mixture during the interval before it is shut off from the burner.

A still further object is to provide such apand to prevent the entrance of residual unburned gas and air to the gasometer when the apparatus is started up after an interval of disuse, as well as other objects, advantages and novel features of design, construction and arrangement hereinafter particularly mentioned, or which will be apparent to those skilled in the art from the following description of oneform of said apparatus which is illustrated, more or less diagrammatically, in the accompanying drawing in which the single figure is a side elevation thereof with certain parts broken away to better show internal construction.

More particularly, a'submerged burner l', preferably of the character of that forming the subject of United States Letters Patent 2,159,759 granted May 23, 1939, is suspended in a tank 2 of which the lower part is desirably conical and the upper part cylindrical and which is provided with a tight cover 3 and at its lower end with a I2, extended therefrom to a mixing device l3 proximatethe connection I which device may be of any suitable character for properly mixing the air and gas supplied to the device through the gas inlet pipe [4. Air is drawn into the blower through a duct I5 desirably provided with an air filter I 6 at its inlet end; in thi duct a pressure responsive valve I1 is disposed to control the volume of air passing to the blower as hereinafter described.

In the gas inlet pipe [4 is an electrically operated shutoff valve 3 which when open permits a full head of gas from any suitable source of supply to enter the pipe and thence pass to the mixing device 13, and when closed prevents passage of any gas thereto.

The amount of gas entering the mixing device when the apparatus is in operation is controlled in proportion to the air supply by any means, generally designated as A, suitable for the purpose such, for example and as diagrammatically illustrated, as the device commercially known as an Askania regulator #S-IBE marketed by the Askania Regulator Company of Chicago, Illinois, which is effective to meter the gas through a metering valve 19 located between shutoff valve l8 and the mixer; as the details of construction and operation of this regulator or of any other which may be employed in lieu thereof form no part of the present invention and are well understood by those familiar with the art, further description thereof would be superfluous.

For conveying the inert gas from tank 2 as it i generated therein by the submerged combustion of the combustible mixture, a conduit 20 is extended from the lid of the tank to any suitable point and thence branched, one branch 2| being extended to a storage tank or gasometer 22 and the other branch 23 to any convenient point desirably above the level of the tank 2 where it is vented to the atmosphere beneath a hood 24. Branch conduit 2| is preferably directed into the gasometer near its base and a baffle may be disposed above the conduit to conthe 3 trol the direction of the entering gases. In branch 2! and thus between conduit 28 and the gasometer is located a quick acting electrically operated butterfly valve 25 and in the other branch 23 alike valve 26, these valves being preferably disposed equidistantly from conduit 20 and so arranged that when one is. open the other is closed; they may be of any suitable construction as long as they are efiective to prevent the passage of gaseous fluids when closed and allow such passage when they are open and are desirably solenoid operated. When the appara: tus is functioning normally, valve 25 is closed and valves I8, 25 are open.

These valves are respectively connected by suitable leads i8, 25, 26 with an electrically actuated control device of any specific construction suitable for the performance of its intended function, one well known commercial instrument adapted for this purpose being that marketed by the-Wheelco Instrument Company of Chicago, Illinois, under. the-name of Limitrol Model T. C. B. .721 and generally designated in the drawing? as L; it receives its actuating current through leads Ii extending'to a suitable source of current supply. It is also connected with a thermo-couple 28 "disposed .at some suitable point proximate the burner, :as below inlet pipe 5, and, speaking generally;..the function of the device L, whatever may beiitslspecific construction, is to actuate valves [8, 2.5,: 26 in accordance with the operation of this thermo-couple in such manner that when some unusual conditionresulting' in extinguishment of burner. I oocurs,.the normal positionsof these valves areuautomatically reversed so that 26 is opened. and" l8 and 2'5 closed as hereinafter more. fully explained.

.Mention has been made of the pressure responsive'valve I! which controls the volume of air entering blower Ill. This valve may be of any suitable-construction adapted for the performanoeof its intended function and is connected bya pipe 29 withnthe gasometer so that if thepressure in the latter. risesdue to less inert gas beingwithdrawnrfrom it than is being then generated, valve I! will operate to decrease the volume of air passing to the blower and'thence to the air inlet pipe H and, in turn, to the mixing'device l3 and vice versa, and as gas regulator A operates to meter th'e gas in-accordance with changes in air supply as'zabove'noted the Proper relative proportions ofa'ir andgas in the mixture passing to the burner are constantly preserved.

Water is supplied to tank 2 through a water inlet --30 extending from its cover 3 to any suitable source of supply, the flow therethrough being'manually controlled by a suitably positioned valve (not shown) so that more or less Water can be admitted 'tothe tank per unit of time, the water levelbeing preferably maintained somewhat above' the burner as indicated by line a by a U- shaped overflow pipe 3| connected into the side of the tank. 7

It will be noted from inspection of the drawing: that conduit 20 is of relatively great diameterand length with the result that a correspondingly long column of the inert gas is maintained therein whenever the apparatus is in normal 010- erati'on; this is a very important feature of the invention as will hereinafter more fully appear.

When starting up the apparatus for the first time'or after an interval of non-use, water is ads mitted to tank 2 substantially to the level a,

blower? i) actuated andg'as valve l 8 opened either manually or through operation of the control mechanism L. Valves 25, 25 are next brought to positions the reverse of those shown in the drawing if not already therein, so that valve 25 is closed and valve 26 open. The burner is then lighted, conveniently by electric ignition mechanism (not shown) interconnected therewith, and the come bustible mixture flowing thru it is thus burned beneath the surface of the water in the tank and the products of combustion rise through the water into the upper portion of the tank and thence pass into conduit 20 through which they continue toward its branches 2i, 23, driving any air within the conduitbefore them. But since valve 25 is now closed, this residual air and the somewhat air-diluted inert gas following it cannot pass to the gasometer but instead is directed through valve 26 into vent 23 and thence into the atmosphere until the upper part of the tank and the conduit are swept clean of-air and impure gas, which requires only a comparatively shOl't interval of time. Valves 25, 26 are then reversed from their previous positions so as to close vent 23 and open branch 2! and thereafter aslong as conditions remain constant the products of combustion, i. e. the inert gas, generated by the burner, ultimately pass to the gasometer. The-reversal of valves 25, 26 to their normal operating position, to which reference has just been made, may be effected manually or thru. operation of control mechanism L depending upon the construction of the valves; when those of the character illustrated are employed it is done in the former way by lifting the counterbalances until the valves are latched in the desired position fromwhich they can be subsequently releasedby the electrical tripping means actuated by said mechanism. Thus, none of the residual air in the upper part of the tank and in the conduit nor any of the first-generatedinert gas 'which may to some extent be diluted thereby can reach the gasometer until normal conditions of operation are established, pending which, of course, a relatively low pressure obtains in'the gasometer and in consequence valve ii is maintained fully open so as to allow the maximum volume of air to pass to blower is and thence into air inlet pipe H.

The apparatus will now continueto-function without further attention as long as the said normal conditions are maintained, the volume of combustible mixture supplied to theburn'er auto: matically varying as above explained in accordance with the pressure in the gasometer through operation of valve I l and the gas metering device A. However, if through accident or any other reason burner i should be extinguished, the en:

suing drop in temperature proximate the thermos couple almost immediately causes the latter' to open or close the circuit to control mechanism-L which then operatesto close gas shutoff valve 48 and trip valves 25, '26, thus closing conduit branch 2! extending to the gasometer and open gas. within the gasometer is thus automatically prevented in caseof any interruption of thenor mal operation of the apparatus and, of course,

substantially coincident with the closing of valve 25and opening of valve 26, gas shutofi valve 18 is also closed, so no wastage of fuel gas occurs following cessation of generation of the inert gas.

By changing the temperature and/or volume of feed water entering the tank, the temperature of the inert gas resulting from the combustion of the mixturein the burner may be varied within limits, while the amountof CO2 contained in the gas may also be controlled in the same way to an appreciable degree since the greater the amount of water supplied per unit of time the greater is the amount of CO2 absorbed therein as the products of combustion pass through it on their way to conduit 28; .it also can be controlled by varying the amount of alkali in the feed water or a secondary alkali wash can be used for its complete removal.

Moreover, the amount of nitric oxide in the inert gas, which is objectionable even in very small quantities because it reacts with water to formnitric acid which attacks the iron mains and other apparatus through which the gas may be conducted, is dependent to a marked degree on the length of time the combustible mixture is in process of combustion in the burner as, in general, the shorter this time the smaller the amount of NO produced. Thus by employing a burner designedto reduce the combustion time as far as practicable, an inert gas substantially devoid of NO may be obtained and so of much greater freedom from this impurity than the inert gases generated in the manner and by the means hitherto customaril employed. This constitutes an important feature of our invention.

it will now be apparent that through the medium of the latter we are enabled to produce inert gas in a convenient way which, as far as we are aware, has not hitherto been proposed, namely by the use of submerged combustion, and that our apparatus is well adapted for the purpose and embodies many advantages and novel features which render it extremely desirable from an operating and maintenance standpoint.

Further, while we have herein described with considerable particularity one form of that apparatus, we do not intend thereby to restrict or confine ourselves specifically thereto, as numerous modifications and changes of design, construction, arrangement and assembly of the var-.

ious instrumentalities comprised therein may be made if desired without departing from the spirit and scope of the invention as defined in the appended claims.

Having thus described our invention, we claim and desire to protect by Letters Patent of the United States:

1. Apparatus of the class described comprising a closed tank, means including an inlet and an outlet adapted to maintain a body of water therein at a predetermined level, a burner disposed inv the tank with its outlet below said level, means for conducting a gaseous combustible mixture to the burner, a gasometer remote from the tank, a conduit adapted to conduct the products of combustion from the upper part of the tank and branched adjacent the gasometer with one branch connected therewith and the other opening to the atmosphere, an electrically actuated normally open shutofi valve in the first branch, a normally closed shutoff valve in the other branch, and thermo-electrically actuated means, including a thermo-responsive element proximate the burner, connected with said valves and automatically operative upon extinguishment of the burner to reverse the normal positions of the valves and thereby close that branch of the conduit connected with the gasometer and open the other branch, the length of said conduit being such as to permit said reversal to take place before any unburned mixture discharged from the burner can reach the gasometer.

2. Apparatus of the class described comprising a closed tank having an overflow outlet adapted to limit the depth of water therein and means for supplying water to the tank, a burner disposed in the tank with its outlet below said overflow outlet, means for directing a combustible gaseous mixture to the burner, a gasometer remote from the tank, a conduit extending from the upper part of the latter and branched proximate the gasometer, one branch connecting there tioned valves whereby under normal conditions of operation the pro-ducts of combustion from the burner pass through the water, thence into the conduit and ultimately through its first branch to the gasometer but are vented to the atmosphere through its other branch upon extinguishment of the burner.

3. Apparatus of the character described comprising a closed tank having means for supplying water to the tank and an overflow outlet determining the maximum level of water contained therein, a burner disposed in the tank having its outlet below said level, an inlet pipe extending from the burner outwardly of the tank, a mixing device connected therewith for mixing air and gaseous fuel to form a combustible mixture, an air inlet pipe connected with said device, means for supplying air under pressure to said pipe including a pressure responsive valve controlling the volume of said air, a gas inlet pipe for conducting gaseous fuel to said device, means automatically regulating the flow of gas to the device in accordance with the volume of air delivered thereto, a gasometer, a conduit leading from the tank for delivering to the gasometer the products of combustion generated in the tank, and a connection between the gasometer and the pressure responsive valve to vary the opening of said valve in accordance with the pressure in the gasometer and so correspondingly control the volume of air delivered to the mixing device.

4. Apparatus of the character described comprising a closed tank having an overflow outlet effective to determine the maximum level of water in the tank and means for supplying water thereto, a burner disposed in the tank having its outlet below said level, an inlet pipe extending from the burner outwardly of the tank, a mixing device connected therewith, an air inlet pipe extending to the mixing device, means for supplying air under pressure through said pipe, a pressure responsive valve associated with said means for controlling the volume of air so supplied, a gas inlet pipe extending to said device, an electrically actuated shutoff valve therein, means between said valve and said device for metering the gas passing to the latter when the shutofi valve is open in accordance with the volume of air delivered to the device, a gasometer remote from the tank, a conduit leading from the tank toward the gasometer and branched proximate gasometer and the otheropening to the atmos-- phere, a similar but normally open electrically actuated shutoff valve in the branch extending to the gasometer, a normally closed shutofi valve in the'other branch, 9, thermo-couple proximate.

the burner, electrical control: means connected therewith and with each of the shutoi'r" valves perative when the thermo-couple is actuated: by a,

decrease in its temperature to close the shutoff valve in the gas inlet pipe; and; reverse the positions of the shutoff valves in the conduitbranches, and a connection between the gasometer and-the pressure responsive valve to controlthe degree of opening of vthe. latter in correspondenceto variations in pressure in the gasometer and thereby Vary'the Volume of air delivered to the mixingdevice, the length. of the conduit being such as to permit the reversal of the valves in the conduit branches following actuation of the thermo-couple before any unburned mixture discharged from the burner can reach the gasometer.

5. In apparatus of the class described, a closed tank, a burner. supported therein in th lower 7 portion thereon a gasometer', a conduit connecting the upper portion of the tank with the gasom-, eter, a mixing device supplyin the burner, conduits for gaseous fuel and air leading to said mixing devioe,.pressure responsive valve means in said air conduit, valve means in said gaseous fuel conduit, means for automatically operating said last named valve, including pressure responsive connections to the, air. and gaseous fuel conduits whereby the. flow of gaseous fuel is proportioned to the flow of air, and a-connection between said gasometer and said valve in the air conduit arranged to operate said valve in response to pressure variations in the gasometer.

6. The'method of producing relatively inert gas;

substantiallyifree of oxides of nitrogen which:

comprisescontinuously admitting to a, substantially, closed-l chamber and withdrawin there; from through asealed overflow a non-combustible liquid/capable, of absorbing said oxides from come bustion products, continuously introducing into thexchamber a combustible mixture-of gaseous fuel andair, effecting combustion of said mixture; beneath the surface of the liquid and discharging the products of combustion into the liquid be-i neath. its surface a; distance adequate to insure substantially complete absorption by the liquid of said oxides contained in said products, collecting the unabsorbed gaseous. products after-their passage through the liquid, initially directing them through; a conduit and into the atmosphere until they have filled the conduit, andthen diverting them after passage through the conduit into a substantially air-freereservoir while excluding air from the chamber, conduit and reservoir,

LAWRENCE K. CECIL. I RUDO P J STENGL. FLOYD B. BEDWELL. 7

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

